1. Field of the Invention
The present invention relates to bonding compositions suitable for dental use. More precisely, the invention relates to bonding compositions suitable for dental use, which exhibit good adhesiveness between a tooth and restorative dental materials in dental treatment, and which are for preventing the growth of cariogenic bacteria in the bonded area.
2. Description of the Related Art
In dental treatment, where partial defects in teeth are restored through prosthesis with restorative dental materials such as, for example, composite resins, monomers, metal alloys and ceramics for dental restoration, dental bonding compositions are often used. However, when such a restorative dental material is directly bonded to the surface of a tooth, it does not exhibit satisfactory bonding strength since it is not adhesive by itself. As a result, the restorative dental material as directly bonded to a tooth will peel off, or, as the case may be, bacteria will penetrate into the bonded interface between the tooth and the restorative dental material to cause secondary caries and odontitis.
In order to solve this problem, various dental bonding methods which include previous application of some tooth surface treating agents to defective teeth to be restored have heretofore been described. Some reports disclose that such tooth surface treating agents improve the bonding strength between a tooth having been pre-treated with any of them and a restorative dental material applied to the surface-treated tooth. For example, (1) Journal of Dental Research Vol. 34, pp. 849-854, 1955 discloses that some acid etching primers 25 improve the bonding strength of restorative dental materials to tooth enamel; (2) Journal of Dental Research, Vol. 63. pp. 1087-1089, 1984 discloses that a primer composition comprising glutaraldehyde, 2-hydroxyethyl methacrylate (hereinafter referred to as HEMA) and water enhances the bonding strength of restorative dental materials to tooth; (3) JP-A-62-223289 discloses that a primer as prepared by adding an acid such as maleic acid, nitric acid or p-toluenesulfonic acid to an aqueous solution of HEMA improves the bonding strength of restorative dental materials to tooth enamel and tooth; (4) JP-A-1-113057 discloses that a primer as prepared by adding a salt of an acid to an aqueous solution of HEMA improves the bonding strength of restorative dental materials to tooth enamel and tooth; and (5) Materials and Instruments for Dental Use, Vol. 9. pp. 65-73, 1990 discloses that a primer as prepared by adding a monomer having an amino acid residue such as N-acryloylaniline or the like to an aqueous solution of HEMA improves the bonding strength of restorative dental materials to tooth enamel and tooth. In addition, (6) JP-A-3-240712 discloses a dental bonding composition as prepared by adding a polymerizable monomer having an acidic group and a curing agent to an aqueous solution of HEMA; and (7) JP-A-4-8368 discloses that adding an amino compound to the dental bonding composition in (6) enhances the ability of the composition to improve the bonding strength of restorative dental materials to teeth.
In particular, a dental bonding method of using a self-etching adhesive primer is an extremely excellent technique, as being easy to perform and provides a high bonding strength to the tooth. The adhesive primer for use in the method comprises an acid (including acidic monomers), a hydrophilic monomer and water, and the method of using it comprises applying the primer to the surface of a tooth and directly applying a bonding material thereto without washing and drying the primer-coated tooth.
However, the self-etching adhesive primer which does not require washing with water is problematic in that the polymerizable monomer will partly remain in the surface layer of tooth even though most of the solvent such as water and the like could be removed through drying with a dental air syringe after its application. The remaining monomer may be polymerized and cured together with the overlaid bonding material by irradiation of light. However, the adhesive primer contains low polymerizable monomers such as hydrophilic monomers and acidic monomers, which could not be polymerized all at once. In order to enhance its polymerizability, some means of improving the adhesive primer have heretofore been tried by adding thereto a photopolymerization initiator, which, however, could not produce the intended effect up to the present. As a result, the polymerization of the monomers in the bonding material (including the adhesive primer) applied to the surface of a tooth is insufficient, and, in a certain period of time after the restoration of the tooth with a restorative dental material, a crevice is formed between the tooth and the butted material to cause marginal leakage, or the butted material is peeled off. Such problems with the adhesive primer have heretofore been often pointed out. In particular, it is said that the problems are remarkable when the bonding material is irradiated by light for a short period of time.
Improving the polymerization curability of the adhesive primer end the bonding material could be attained in some degree by increasing the amount of the photopolymerization initiator in those compositions. Increasing the amount of the initiator too much in those compositions is problematic in that the initiator remaining in the cured products of the compositions will be much released out, since the initiator has no polymerizable group, and, in addition, the mechanical strength of the cured products is lowered and the cured products are discolored with the lapse of time. In that condition, aesthetic tooth crown repairing is impossible. For these reasons, adding too much initiator to the compositions is impracticable.
There is still another problem of secondary caries and odontitis that may be caused by the penetration of bacteria into the bonded interface between tooth and the restorative dental material applied thereto, in addition to the bonding durability failure in the bonding material used. The problem is often pointed out as serious.
For preventing the penetration of bacteria into the bonded interface, antibacterial dental bonding materials have been proposed. For examples JP-A-1-17107 discloses dental cement that contains an antibacterial agent. JP-A-2-16176 and B-198723 disclose a pre-treating agent for dental use that contains a quaternary alkylammonium salt. In these, they do not specifically refer to the antibacterial property of the pre-treating agent, but the quaternaryalkylammonium salt used will have antibacterial ability. However, the antibacterial agent and the quaternary alkylammonium salt have no polymerizable group, and will be therefore released out into the mouth after the dental bonding composition comprising any of them has been polymerized and cured on a tooth. Prior to their dental application, therefore, the antibacterial agent and the quaternary alkylammonium salt require complete safety evaluation. Another problem with them is that the antibacterial agent and the quaternary alkylammonium salt do not exhibit the antibacterial ability for a long period of time.
JP-A-6-9725 and 7-215814 disclose dental compositions containing an antibacterial polymerizable monomer and an acid group-having polymerizable monomer. The antibacterial property as referred to in these is the non-releasing antibacterial property of the polymerized (or cured) products of the dental compositions. Here, the cured products do not release the antibacterial component from them. These publications indicate that the cured products as formed through copolymerization of the antibacterial polymerizable monomer and the other monomer exhibit the antibacterial ability on their surface. Specifically, in the cured polymer products of the dental compositions proposed, the unpolymerized antibacterial compound is exposed out on the surface of the cured polymer, and it may attenuate the bacteria having adhered on the surface of the cured products, but could not kill the bacteria existing in the fine structure of the bonded interface of tooth tubules.
One means of solving the problem has been proposed in JP-A 8-157318, which discloses an antibacterial adhesive primer comprising an antibacterial polymerizable monomer, an acid group-containing polymerizable monomer, an alcoholic hydroxyl group-containing polymerizable monomer, water and a polymerization catalyst.
The technique proposed is characterized in that an antibacterial polymerizable monomer is added to the adhesive primer for killing bacteria in and around teeth while, at the same time, attaining decalcification of teeth, and that the polymerized and cured product of the primer composition exhibits a non-releasing antibacterial ability on its surface. Therefore, this is an extremely useful technique. However, the adhesive primer contains a large amount of slightly-volatile components such as the acid group-containing polymerizable monomer and the alcoholic hydroxyl group-containing polymerizable monomer. Therefore, the probability of contact between bacteria and the antibacterial polymerizable monomer in a resultant product is low, and the adhesive primer could not satisfactorily express the antibacterial ability. In addition, when cured on a tooth the adhesive primer gives a layer of a copolymer of the antibacterial polymerizable monomer and other polymerizable monomers in and around the bonded interface between its cured product and the tooth. However, since the proportion of other polymerizable monomers to the antibacterial monomer is large, the adhesive primer could not still produce a satisfactory antibacterial effect.
Greatly increasing the amount of the antibacterial polymerizable monomer or greatly decreasing the amount of the acid group-containing polymerizable monomer and that of the alcoholic hydroxyl group-containing polymerizable monomer in the adhesive primer could improve the antibacterial ability of the adhesive primer in some degree, which, however, is not practicable as greatly lowering the bonding force of the adhesive primer to a tooth.
A composition comprising an antibacterial polymerizable monomer and a volatile solvent is known. For example, as in JP-A-9-67546, an antibacterial polymerizable monomer may be added to an adhesive composition comprising a monomer capable of bonding to metal and a volatile solvent. However, the adhesive composition disclosed in JP-A-9-67546 is directed to modification of the surface of metal, and nothing is referred to therein that relates to a technique of killing bacteria in and around a tooth. The present inventors tested the compositions of the examples disclosed in JP-A-9-67546, but the compositions did not have high bonding strength to a tooth.
JP-A-10-236915 discloses an antibacterial caries-detecting liquid that comprises an antibacterial polymerizable monomer, a dye, and water and/or a water-miscible solvent. Basically, this liquid is applied to a tooth before the affected tooth is removed from the tooth with a cutting tool, thereby killing the cariogenic bacteria that exist in and around the affected tooth while differentiating the affected tooth from the non-affected healthy tooth, and the technique disclosed is very useful. However, most of the antibacterial polymerizable monomer in the antibacterial caries-detecting liquid is removed along with the affected tooth which is removed with a cutting tool. In that condition, a high concentration of the monomer could not be in and around the tooth treated with the liquid. Therefore, even though the liquid could kill the cariogenic bacteria existing in and around tooth, it is almost completely ineffective against the cariogenic bacteria that may penetrate into the restored area of a tooth, and therefore could not prevent the growth of the cariogenic bacteria penetrated into that area after treatment.
Accordingly, there remains a need for compositions and methods which overcome the problems described above.
It is an object of the present invention to provide bonding compositions suitable for dental use.
It us another object of the invention to provide bonding compositions which can inhibit the growth of cariogenic bacteria in the bonded area of a tooth when restored with a restorative dental material, thereby preventing secondary caries and odontitis around that area, and which can enhance the bonding strength, especially the bonding durability of the restorative dental material, to a tooth.
To accomplish the objects noted above, the present inventors have assiduously studied the problem of how to prevent the growth of cariogenic bacteria in the bonded area of tooth as restored with a restorative dental material and of how to entrance the bonding curability of a restorative dental material and a tooth as restored with the material, and, as a result, have discovered th e following novel techniques.
An antibacterial primer comprising a specific antibacterial polymerizable monomer and a volatile solvent is applied around the surface of a tooth, and then dried spontaneously or through dental air blowing so as to make a high concentration of the antibacterial, polymerizable monomer on the tooth surface, thereby killing the bacteria having adhered on the surface of tooth of the tooth. Thereafter, an adhesive composition that comprises an acid group-containing polymerizable monomer, a polymerizable monomer and a polymerization initiator is applied to the area of the tooth, and is cured along with the antibacterial monomer previously applied thereto, thereby forming an antibacterial polymer layer having a high concentration at the interface between the tooth and the bonding material. Bacteria that may penetrate into the bonded interface are killed by the antibacterial polymer layer, and the polymer existing in the bonded interface retains its antibacterial ability for a long period of time.
The adhesive composition described above is composed of two compositions, one being an adhesive primer that comprises an acid group-containing polymerizable monomer, a hydrophilic polymerizable monomer and water, and the other being a bonding agent that comprises a polymerizable monomer and a polymerization initiator. The adhesive composition of this type is a so-called self-etching adhesive component. The photopolymerization initiator in the bonding agent contains both an acylphosphine oxide compound and an xcex1-diketone compound. The adhesive primer is first applied to a tooth and is cured along with the bonding agent within a short period of time to form a hard cured layer on the tooth by which the bonding durability of the cured layer to a tooth is enhanced.
Based on the techniques as described above, the present inventors have discovered that the bonding compositions according to the present invention significantly prevent the growth of cariogenic bacteria in the bonded area between tooth and restorative dental material applied thereto and enhance the bonding strength, especially the bonding durability between tooth and a restorative dental material applied thereto, as compared with conventional bonding compositions.
Accordingly, the objects of the invention, and others, may be accomplished with an antibacterial bonding composition suitable for dental use, comprising:
(A) an antibacterial primer comprising (i) an antibacterial polymerizable monomer containing an ethylenic unsaturated group and at least one cationic group selected from the group consisting of ammonium bases, pyridinium bases and phosphonium bases, and (ii) a volatile solvent; and
(B) an adhesive composition comprising (i) a first polymerizable monomer containing an acid group, (ii) a second polymerizable monomer, and (iii) a polymerization initiator, wherein (A) and (B) are packaged separately.
The objects of the invention may also be accomplished with an adhesive composition suitable for dental use, comprising:
(P) an adhesive primer comprising (i) a polymerizable monomer containing an acid group, (ii) a hydrophilic polymerizable monomer, and (iii) water; and
(Q) a bonding agent comprising (i) a polymerizable monomer, (ii) an acylphosphine oxide compound, and (iii) an xcex1-diketone compound.
The objects of the invention may also be accomplished with an antibacterial bonding composition suitable for dental use, comprising:
(A) an antibacterial primer comprising (i) an antibacterial polymerizable monomer containing an ethylenic unsaturated group and at least one cationic group selected from the group consisting of ammonium bases, pyridinium bases and phosphonium bases, and (ii) a volatile solvent;
(P) an adhesive primer comprising (i) a polymerizable monomer containing an acid group, (ii) a hydrophilic polymerizable monomer, (iii) water, and (iv) a polymerization initiator; and
(Q) a bonding agent comprising a (i) polymerizable monomer, (ii) a polymerizable monomer containing an acid group, (iii) an acylphosphine oxide compound, and (iv) an xcex1-diketone compound,
where the ratio of the acylphosphine oxide compound to the xcex1-diketone compound is 1:0.01 to 1:0.5.
The objects of the invention may also be accomplished with a composition suitable for dental use, comprising:
(a) an antibacterial polymerizable monomer containing an ethylenic unsaturated group and at least one cationic group selected from the group consisting of ammonium bases, pyridinium bases and phosphonium bases;
(b) an a polymerizable monomer containing an acid group;
(c) an additional polymerizable monomer; and
(d) a polymerization initiator.
The objects of the invention may also be accomplished with a method of providing an antibacterial coating on a tooth, comprising curing the composition described above on the tooth.
The objects of the invention may also be accomplished with a method of applying an antibacterial coating to a tooth, comprising:
applying to a tooth a first composition comprising (i) an antibacterial polymerizable monomer containing an ethylenic unsaturated group and at least one cationic group selected from the group consisting of ammonium bases, pyridinium bases and phosphonium bases, and (ii) a volatile solvent;
removing at least a portion of the volatile solvent;
applying to a tooth a second composition comprising (i) a first polymerizable monomer containing an acid group, (ii) a second polymerizable monomer, and (iii) a polymerization initiator; and then
curing the applied compositions.
A more complete appreciation of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description.